Tensioner for Engine with Large and Stable Damping and Minimum Deflection o f Shaft

ABSTRACT

A tensioner includes a base, a tension arrangement rotatable at the base, a damping member being rotated in a loading direction by the tension arrangement, and an elastic member biasing against the damping member. The position of the damping member depends by the layout geometry of the specific application and is directly in opposition to the hub load. The reaction force of the cylindrical surface of the base on the damping member is very near to the plan of the external forces represented by the hub load to minimize the deflection of the shaft. The tension arrangement is rotated to push the damping member for generating a first positive tension between the damping member and the base, and to expand the elastic member radially for generating a second positive tension between the elastic member and the damping member, so as to enhance a damping force of the tensioner.

CROSS REFERENCE OF RELATED APPLICATION

This is a Divisional application that claims priority to U.S.non-provisional application, application Ser. No. 14/621,333, filed Feb.12, 2015, the entire contents of each of which are expresslyincorporated herein by reference.

NOTICE OF COPYRIGHT

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to any reproduction by anyone of the patent disclosure, as itappears in the United States Patent and Trademark Office patent files orrecords, but otherwise reserves all copyright rights whatsoever.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to a tensioner for engines, and moreparticularly to a tensioner for an engine with large and stable dampingand minimum deflection of the shaft.

2. Description of Related Arts

Endless transmission device, such as belt drive or chain drive, iscommonly used for transmitting power from one component to the otherduring the operation of engine. However, once the tooth profile of theendless transmission device is worn, slippage will occur. As a result,the endless transmission device not only losses its power transmittingability but also can be noisy. If the slippage of the endlesstransmission device keeps occurring, the noise will become serious. Thisnoise problem from the slippage of the endless transmission device isoften the biggest problem for the driver of the vehicle in pursuit ofsilent. In addition, the slipping of the endless transmission devicewill also shorten the service life span thereof. The damaged endlesstransmission device will damage the engine as well. Therefore, atensioner is required for incorporating with the endless transmissiondevice to maintain the tension thereof. In other words, the belt driveor the chain drive can be remained in a stable tension state by thetensioner in order to prevent the belt drive or the chain drive fromslipping or tooth-skipping.

In the current market, an automatic belt tensioner with a dampingmechanism is able to solve the vibration and noise problems from thefront assembly of the engine. However, most of the existing dampingmechanism technologies have the common problems of lacking a dampingforce with the severe attenuation of the damping force.

Referring to FIGS. 6 to 9 of the drawings, these are the two commonconventional designs utilized in the current market. The firstconventional tensioner comprises a dish-shaped elastic member 25 beingsqueezed along its axis direction to be deformed by a pressing force, soas to generate an axial force to a damping member 26 and a cover 27,wherein the damping member 26 and the cover 27 are closely connectedwith each other to define a connection surface 28. Since the dampingmember 26 is made of wearable materials, and the cover 27 and thedamping member 26 is rotated relatively during the operation of thetensioner, the connection surface 28 has friction coefficients. So afriction force, which is generated between the damping member 26 and thecover 27 during the relative rotation operation therebetween, isdetermined by the pressing force provided by the dish-shaped elasticmember 25. In addition, the elastic member 25 is made of material withhigh rigidity, so that a small amount of compression of the elasticmember 25 will generate a relatively large amount of axial force. Inother words, even if the change of the compression displacement of theelastic member 25 is small, the change of the pressing force producedtowards the axial direction will relatively large. Normally, therigidity level of the elastic member is approximately 2000 N/mm, so thatall relevant parts of the tensioner will be collected towards the axialdirection. In addition, since the axial force becomes very large, thedamping will be unstable. Furthermore, after the tensioner is used for along time, a clearance between the damping member 26 and the cover 27will become very large due to the friction force therebetween.Therefore, the compression displacement of the elastic member 25 willgradually decrease, and the damping force generated from the elasticmember 25 will normally be dropped more than 50%. Therefore, largeamount of deformation of the elastic member 25 is required in order tomaintain enough frictional forces between the damping member 26 and thecover 27. However, the compression displacement of the elastic member ofthe tensioner is constant in the initial design, so the frictionalforces between the damping member 26 and the cover 27 will graduallydecrease during the operation of the tensioner. Accordingly, thetensioner cannot be designed to provide sufficiently large amount offriction forces. For example, in order to provide 500 N of frictionalforces by the tensioners, the elastic member 25 must be designed toprovide at least 1000 N of frictional forces. Conversely, if the elasticmember 25 is designed to generate 500 N of frictional forces, theremaining frictional forces provided by the elastic member 25 will bedecreased to 250 N or even lower after the tensioner is in use for aperiod of time. In other words, the biggest drawback of the abovementioned tensioner is that the frictional forces are dramaticallydecreased with use, so that the attenuation of damping is serious.Therefore, the tensioner must be maintained frequently in order to meetthe dampening requirements.

Referring to FIG. 8 and FIG. 9 of the drawings, a second conventionaltensioner is illustrated, wherein the second conventional tensionercomprises an elastic member 30 which is loaded after assembling. Theelastic member 30 is loaded by means of pulling operation, wherein theelastic member 30 comprises a first hook end 32 and an opposed secondhook end 33, wherein the first hook end 32 is attached with an annulardamping member 29, and the second hook end 33 is attached with a tensionarm 31. The annular damping member 29 is installed in an inner diameterof the elastic member 30, wherein an outer surface of the damping member29 is contacted with the inner surface of the elastic member 30, and theinner surface of the damping member 29 is contacted with a top surface34 of the tension arm 31, such that the frictional forces will begenerated between the damping member 29 and the tension arm 31. In otherwords, the damping member 29 is located between the elastic member 30and the tension arm 31. When the tensioner is operated, the dampingmember 29 is rotated with respect to the top surface 34 of the tensionarm 31 to generate frictional forces, wherein the diameter of theelastic member 30 is gradually decreased during the rotation of thetension arm 31, so as to generate a pressing force to the damping member29. So, the damping member 29 is closely contacted with the tension arm31 by the pressing force, to provide sufficiently large amount offriction force between the damping member 29 and the tension arm 31.However, the above mentioned structure has the following disadvantages.Although the attenuation of the frictional forces is lower than thefirst conventional tensioner, the second conventional tensioner only canprovide low power of frictional force. Since the positive frictionalforce only comes from one source, the ratio of the torque of the dampingtorque and torque of the elastic member cannot exceed 0.6, which cannotmeet some of the large damping system requirements. Since the pressingforces applied on the damping member 29 is determined by the change ofthe inner diameter of the elastic member 30, the cost for manufacturingthe elastic member 30 to provide large amount of damping forces will beincreased correspondingly. In addition, the change of the inner diameterof the elastic element 30 is determined by the tensile of the elasticelement 30. In other words, the change of the inner diameter of theelastic member 30 is determined by the tensile of the elastic member 30,and then the pressing forces applied on the damping member 29 aredetermined by the change of the inner diameter of the elastic member 30,so the damping member 29 cannot provide large amounts of frictionalforces. Therefore, it is preferred that the pressing forces applied onthe damping member 29 is directly determined by the tensile of theelastic member 30, so as to minimize the energy loss during thetransformation process. Conversely, the tensile for the damping member29 is amplified via the change of the inner diameter of the elasticmember 30 as well as that the damping member 29 is worn. In other words,the dimension change of the damping member 29 due to the wear and tearthereof is made up by the dimension change of the inner diameter of theelastic member 30. However, the change of the inner diameter of theelastic member 30 and the tensile thereof are mutually corresponding.So, it is preferred that the elastic member 30 should have small changeof the inner diameter and large tensile. As a result, the wear and tearof the damping member 29 has stronger effect to the frictional forces.In other words, the frictional forces are decreased after the tensioneris operated during a period of time, and the attenuation of the frictionforce is still large.

SUMMARY OF THE PRESENT INVENTION

A main object of the present invention is to provide a tensioner forengines, wherein the tensioner can provide a large and stablesignificant damping effect, and the damping will not be dramaticallydecreased during the operation of the tensioner. Furthermore, thedeflection of the shaft is minimized.

According to the present invention, the foregoing and other objects andadvantages are attained by a large damping and low attenuation tensionerfor engines, comprising a base, a retention arrangement, a tensionarrangement, an elastic member disposed inside the base, and a dampingmember arranged inside the base. The base has an inner cylindricalsurface, and the damping member has a friction surface, wherein thefriction surface and the inner cylindrical surface are contacted witheach other to generate a frictional force during a relative movementtherebetween. The tension arrangement comprises a projected member,wherein while the tension arrangement is rotated with respect to thebase, the projected member pushes the damping member to rotate. Theelastic member is a cylindrical and helical torsion spring, and theelastic member comprises two end faces, which are a first end surfaceand a second end surface, wherein the first end surface is contactedwith the damping member, and the second end surface is contacted withthe base. Therefore, while the elastic member is radially expandedtowards a loading direction, the damping member is pushed to closelycontact with the inner cylindrical surface of the base by the outercircumference of the elastic member.

The frictional force is generated by a relative movement between theinner cylindrical surface of the base and the damping member, such thatthe tension arrangement is rotated with respect to the base for pushingthe damping member, and the elastic member is compressed by the dampingmember, so as to provide the torque for the tensioner, which can alsogenerate a first positive tension. At the same time, while the elasticmember is radially expanded, the damping member will be pushed toclosely contact with the inner cylindrical surface of the base, so as togenerate a second positive tension. Due to that the first and secondpositive tensions are generated at the same time, a huge amount offrictional damping force is generated. The ratio of the torque for thedamping and the elastic member is larger than 0.85. Since the firstpositive tension and the second positive tension are provided from thetorque of the elastic member, the first and second positive tension havea linear correlation with the torque of the elastic member. Since theattenuation of the frictional force is determined by the attenuation ofthe torque of the elastic member, the attenuation of the frictionalforce will not exceed 15% during the entire life-span of the tensionerof the present invention.

Preferably, the damping member comprises two end surfaces, which is athird end surface and a fourth end surface, wherein the third endsurface and the fourth end surface are closely contacted with the firstend surface of the elastic member and the projected member of thetension arrangement respectively, such that while the elastic member isrotated towards the loading direction, the first positive tension willbe generated by the elastic member and the projected member.

Preferably, the damping member comprises an inner cylindrical surface,wherein while the elastic member is radially expanded, the outercircumference of the elastic member is pressed towards the innercylindrical surface of the damping member, so as to generate a secondpositive tension.

Preferably, the damping member comprises a damping cover and a dampingbody, wherein the damping body is made of rigid material, and thedamping cover is made of elastic material, and mating tooth arranged inthe joint portion formed between the damping body and the damping cover.

Preferably, a large damping and low attenuation tensioner for enginescan provide a huge amount of frictional force, and the attenuation ofthe frictional force is relatively small during the entire life-spancircle.

Another object of the present invention is to provide a large dampingand low attenuation tensioner, which can provide a large frictionalforce and further solve problems of vibrations and noise generated fromthe front parts of the engines.

Another object of the present invention is to provide a large dampingand low attenuation tensioner, which can guarantee a low attenuation ofthe damping, such that the tensioner has a longer life-span to maintaina normal working operation for the engine. Furthermore, the tensioner isdesigned to minimize the deflection of the shaft.

Another object of the present invention is to provide a large dampingand low attenuation tensioner, wherein two positive tensions generatedtowards the same direction are applied on the damping member, such thatthe overall positive tension applied on the damping member is enhancedto achieve a high damping tensioner.

Another object of the present invention to provide a large damping andlow attenuation tensioner, wherein the positive tensions applied on thedamping member are provided by the torque generated from the elasticmember, such that the strength of the positive tension is determined bythe amount of the deformation of the elastic member.

Another object of the present invention provides a low attenuation andlarge damping tensioner, wherein the dimension change of the dampingmember has relatively small impact with respect to the torsion angle ofthe elastic member, in such a manner that the change of the torque isextremely small, so as to maintain a constant amount of positive tensionon the damping member.

Additional advantages and features of the invention will become apparentfrom the description which follows, and may be realized by means of theinstrumentalities and combinations particular point out in the appendedclaims.

Still further objects and advantages will become apparent from aconsideration of the ensuing description and drawings.

These and other objectives, features, and advantages of the presentinvention will become apparent from the following detailed description,the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a large damping and low attenuationtensioner for engines according to a first preferred embodiment of thepresent invention, illustrating a belt wrapping on the tensioner.

FIG. 2 is a sectional view of a large damping and low attenuationtensioner for engines according to the above first preferred embodimentof the present invention.

FIG. 3 is a sectional view of a large damping and low attenuationtensioner for engines according to the above preferred embodiment of thepresent invention, illustrating a forcing relation between all parts ofthe tensioner.

FIG. 4 is a perspective view of a damping member of a large damping andlow attenuation tensioner for engines according to the above preferredembodiment of the present invention.

FIG. 5 is a perspective view of a tension arrangement of a large dampingand low attenuation tensioner for engines according to the abovepreferred embodiment of the present invention.

FIG. 6 is an exploded view of a conventional tensioner.

FIG. 7 is a side view of the above mentioned conventional tensioner.

FIG. 8 is an exploded view of another conventional tensioner.

FIG. 9 is a side view of the above mentioned another conventionaltensioner.

FIG. 10 and FIG. 11 are perspective views of a tensioner according to asecond preferred embodiment of the present invention.

FIG. 12 is an exploded view of a tensioner according to the abovementioned second preferred embodiment of the present invention.

FIG. 13 is an exploded view of a damping member according to the abovementioned second preferred embodiment of the present invention,illustrating the damping member coupled on the elastic member.

FIG. 14 is a perspective view of a base according to the above mentionedsecond preferred embodiment of the present invention.

FIG. 15 is a side view of the tensioner according to the above mentionedsecond preferred embodiment of the present invention.

FIG. 16 illustrates different tensions distributed at the tensioneraccording to the above mentioned second preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description is disclosed to enable any person skilled inthe art to make and use the present invention. Preferred embodiments areprovided in the following description only as examples and modificationswill be apparent to those skilled in the art. The general principlesdefined in the following description would be applied to otherembodiments, alternatives, modifications, equivalents, and applicationswithout departing from the spirit and scope of the present invention.

Referring to FIG. 1 and FIG. 2 of the drawings, a large damping and lowattenuation tensioner for engines according to a preferred embodiment ofthe present invention, wherein the tensioner comprises a base 3, aretention arrangement 8 serving as a core shaft, a tension arrangement6, an elastic member 4 disposed within the base 3 in a non-rotatablymovable manner, and a damping member 5, such as a damping shoe, arrangedinside the base 3, wherein the elastic member 4 is arranged to biasagainst an inner surface of the damping member 5. The tensionarrangement 6 is rotatably coupled with the base 3 via the core shaft ofthe retention arrangement 8, such that the elastic member 4 and thedamping member 5 are closely sealed inside the base 3 and the tensionarrangement 6.

The base 3 has an inner cylindrical surface 13, and the damping member 5has a friction surface 14, wherein the friction surface 14 and the innercylindrical surface 13 are frictionally contacted with each other togenerate a frictional force during a relative movement therebetween. Thetension arrangement 6 comprises a projected member 19, wherein while thetension arrangement 6 is rotated with respect to the base 3, theprojected member 19 will push the damping member 5 to rotate. Theelastic member 4 is a cylindrical torsion spring. Preferably, theelastic member 4 has a helical structure. The elastic member 4 comprisestwo end faces, which are a first end surface 16 and a second end surface17, wherein the first end surface 16 is preferably defined at an uppersurface of the elastic member 4, and the second end surface 17 ispreferably defined at a bottom surface of the elastic member 4. Inaddition, the first end surface 16 couples with the damping member 5,and the second end surface 17 couples with the bottom side of the base3. It is worth mentioning that since the upper surface of the elasticmember 4 is symmetrically arranged with the bottom surface of theelastic member 4, the first end surface 16 and the second end surface 17are symmetrically arranged with each other. Furthermore, the first endsurface 16 and the second end surface 17 are not flat surfaces, so whileeither the first end surface 16 or the second end surface 17 are placedon a flat surface, the elastic member 4 is inclinedly and verticallyarranged with respect to the flat surface.

As shown in FIG. 3, the damping member 5 is able to rotate towards anunloading direction and a loading direction by being pushed by theprojected member 19. The damping member 5 has a sliding cavity 23 formedat the inner surface of the damping member 5, and the elastic member 4is frictionally contacted with a sliding surface of the sliding cavity23 of the damping member 5, i.e. the inner surface thereof. Therefore,while the damping member 5 is rotated in the loading direction, theelastic member 4 is radially expanded, and then the projected member 19is pushed to closely contact with the inner cylindrical surface 13 ofthe base 3 by an outer circumference of the elastic member 4. In otherwords, while the damping member 5 is rotated in the unloading direction,the elastic member 4 is compressed, so the projected member 19 is movedaway from the inner cylindrical surface 13 of the base 3.

It is worth mentioning that the base 3 and the retention arrangement 8are connected with each other by means of interference fit, wherein thetension arrangement 6 is rotatably coupled with the retentionarrangement 8 to ensure the elastic element 4 and the damping member 5to be retained between the bottom of the base 3 and the tensionarrangement 6. The tensioner further comprises a pulley 9, a dust cover10, a bearing 11, and a screw 12, wherein the pulley 9, the dust cover10, the bearing 11, and the screw 12 are arranged to corporate with thetension arrangement 6, so as to rotate with respect to the retentionarrangement 8. In addition, the tension arrangement 6 and the retentionarrangement 8 are separated by a bush 7.

It is worth mentioning that the position of the damping member 5 dependsby the layout geometry of the specific application and is directly inopposition to the hub load P indicated in FIG. 1.

A second significant aspect of the design is that the reaction of thecylindrical surface 13 of the base 3 on the damping member 5 is verynear to the plan of the external forces represented by the hub load P,as shown in FIG. 1, as to minimize the deflection torque taken by theshaft. In other words, the above features will minimize the deflectionof the shaft of the retention arrangement 8 due to the external force P.

The damping member 5 has an arc-shape defining two ends, which are athird end surface 15 and a fourth end surface 18, wherein the third endsurface 15 couples with the first end surface 16 of the elastic member4, and the fourth end surface 18 couples with the projected member 19 ofthe tension arrangement 6. In addition, while the elastic member 4 isradially expanded as well as that the damping member 5 is rotatedtowards the loading direction, the damping member 5 and the projectedmember 19 are both rotated towards the loading direction to generate aresultant force, which is a first positive tension. Accordingly, whenthe elastic member 4 is radially expanded, the outer circumference ofthe elastic member 4 is closely pressed towards the sliding surface ofthe sliding cavity 23 of the damping member 5, so as to generate asecond positive tension. It is worth mentioning that both the first andsecond positive tensions are in form of frictional forces.

The damping member 5 comprises a damping cover 20 and a damping body 21,wherein the damping body 21 is made of rigid material. The damping body21 can be made of cast steels, powder metallurgy components, or othermaterial having a predetermined amount of strength and an easily-moldingstructure. The damping cover 20 is made of elastic material, wherein theelastic material can be wear-resistant nylon. In order to improve thefrictional coefficient of the damping cover 21, a plurality of anti-slipstrips is provided on the damping cover 21. During the manufacturing ofthe damping member 5, the elastic material is mold-injected on an outercircumferential surface of the damping body 21 to form the damping cover20. The damping cover 20 and the damping body 21 are combined with eachother to define a joint portion, wherein a plurality of spaced apartmating teeth 22 is arranged in the joint portion. The mating teeth 22are concavo-convex concerted mating teeth extended from the damping body21 to the damping cover 20, so as to restrict the relative rotationalmovement between the damping body 21 and the damping cover 20. Inaddition, the damping body 21 is a semicircular structure, and thesliding cavity 23 of the damping member 5 is formed at the inner surfaceof the semicircular structure of the damping body 21. Furthermore, thedamping cover 20 covers on the outer surface of the damping body 21 as asleeve thereof, so that the damping cover 20 also has a semicircularstructure.

As shown in FIG. 1, the tensioner is operated in an equilibriumsituation, a first band segment 1 and a second band segment 2, which aredefined as tension forces F, are combined to form an action force P ofthe hub load (resultant force at the band segment 1 and the second bandsegment 2) on the tensioner.

Referring to FIG. 3 and FIG. 5, the action force P is applied to acontacted portion between a side face of the projected member 19 and thefourth end surface 18 of the damping member 5, so the action force P istransmitted to the damping member 5 to generate an opposite reactionforce P′. Then, the action force P is continuously transmitted to acontact portion between the third end surface 15 of the damping member 5and the first end surface 16 of the elastic member 4, so as to transmitthe action force P to the elastic member 4 to generate a second reactionforce P1. The action force P and the second reaction force P1 iscombined to form a second resultant force P2, wherein the secondresultant force P2 is a normal positive force applied on the dampingmember 5, which is the first positive tension as mentioned. Furthermore,an additional frictional force is generated between the innercylindrical surface 13 of the base 3 and a frictional surface 14 of thedamping member 5. It is worth mentioning that action force P is offsetby a torque force W generated by the elastic member 4, and the secondend surface 17 of the elastic member 4 is locked by the base 3, so therotation of the elastic member 4 is stopped.

Referring to FIG. 3 of the drawing, the elastic member 4 is rotatedtowards the loading direction by the action force P, such that the outercircumference of the elastic member 4 is radially expanded to pressagainst the sliding surface of the sliding cavity 23 of the dampingmember 5, so as to generate a first radial distribution pressure Δf, andthen a third resultant force P3 is generated at a normal direction ofthe friction surface 14 of the damping member 5, wherein the thirdresultant force P3 is the second positive tension as mentioned above. Inaddition, the outer circumference of the elastic member 4 is pressedagainst an inner cylindrical surface 24 of the tension arrangement 6 togenerate a second radial distribution pressure Δf, and then a thirdopposite resultant force P3′ is generated at a normal direction of theinner cylindrical surface 24 of the tension arrangement 6, wherein thethird opposite resultant force P3′ is offset by the third resultantforce P3.

It is worth mentioning that the second resultant force P2 (the firstpositive tension) and the third resultant force P3 (the second positivetension) are both applied on the damping member 5 at the same time, sothe tensioner can provide a relatively large amount of frictional force.

According to the preferred embodiment of the present invention, thetensioner of the present invention is a high damping tensioner and theattenuation of the damping thereof is relatively small during the entirelife cycle thereof. Additional frictional force is generated between theinner cylindrical surface 13 of the base 3 and the friction surface 14of the damping member 5. The tension arrangement 6 is rotated withrespect to the base 3 to push the damping member 5, and then the elasticmember 4 is actuated to rotate by the damping member 5 to generate thetorque force, wherein the elastic member 4 is incorporated with thetension arrangement 6 to generate a second resultant force, which is thefirst positive tension for the tensioner.

At the same time, while the elastic member 4 is rotated towards theloading direction, the outer circumference of the elastic member 4 isradially expanded to activate that the damping member 5 closely contactswith the inner cylindrical surface 13 of the base 3, so as to generatethe second positive tension for the tensioner. Since the first andsecond positive tensions are reacted simultaneously, a large amount offrictional force can be generated from the tensioner of the presentinvention, wherein the ratio of the torque of the damping and theelastic member can be 0.85 or even higher. Since the first positivetension and the second positive tension are derived from the springtorque generated from the elastic member 4, the abrasion loss of thedamping cover 21 has slightly small effect to the angle of the torquefor the elastic member 4 as well as that the elastic member 4 isradially expanded towards the loading direction, so the change of thetorque of the elastic member 4 is relatively small. Since theattenuation of the frictional force is determined by the attenuation ofthe torque of the elastic member 4, the attenuation of the frictionalforce will not exceed 15% during the entire life-span of the tensionerof the present invention.

Referring to FIG. 10 to FIG. 15 of the drawings, a large damping and lowattenuation tensioner for engines according to a second preferredembodiment of the present invention, wherein the tensioner comprises abase 10A, a retention arrangement 50A, a tension arrangement 40A, anelastic member 20A disposed within the base 10A, and a damping member30A arranged inside the base 10A. The tension arrangement 40A isrotatably arranged on the base 10A via the retention arrangement 50A,such that the elastic member 20A and the damping member 30A are closelysealed inside the base 10A and the tension arrangement 10A.

As shown in FIG. 14, the base 10A has a thrust groove 102A formed on abottom of the base 10A at a mid-portion thereof, and a mounting cavity101A integrally communicated with the thrust groove 102A. In otherwords, the thrust groove 102A is defined on the bottom portion of thebase 10A. Since the elastic member 20A is disposed within the base 10A,the elastic member 20A is disposed in the mounting cavity 101A, and abottom end portion of the elastic member 20A is disposed on the thrustgroove 102A.

As shown in FIG. 13, the elastic member 20A is a cylindrical torsionspring, and the elastic member 20A is a helical structure. The elasticmember 4 comprises two end faces, which are a first end surface 202A anda second end surface 203A, wherein the first end surface 202A is definedat a first surface 204A of the elastic member 20A, and the second endsurface 203A is defined at a second surface 205A of the elastic member20A. In addition, the first surface 204A of the elastic member 20A issymmetrically arranged with the second surface 205A of the elasticmember 20A, so the first end surface 202A and the second end surface203A are symmetrically arranged with each other also. Furthermore, thefirst surface 204A and the second surface 205A of the elastic member 20Aare not flat surfaces, so while either the first surface 204A or thesecond surface 205A of the elastic member 20A are placed on a flatsurface, the elastic member 20A is inclinedly and vertically arranged onthe flat surface.

Accordingly, the elastic member 20A is disposed inside the base 10A, andthe elastic member 20A is perpendicularly arranged with respect to theinner bottom surface of the base 10A, so that the shape of the thrustgroove 102A must match with either the first surface 204A or the secondsurface 205A of the elastic member 20A. The depth of the thrust groove102A has different gradients, wherein the largest depth of the thrustgroove 102A matches with the first end surface 202A or the second endsurface 203A of the elastic member 20A. In other words, the depth of thethrust groove 102A is gradually decreased to match with the gradients ofeither the first end surface 202A or the second end surface 203A of theelastic member 20A. Therefore, while the elastic member 20A is disposedinside the mounting cavity 101A and the thrust groove 102A, the base 10Ais perpendicular to the either the first end surface 202A or the secondend surface 203A of the elastic member 20A. In addition, one end of thethrust groove 102A defines a stopping surface 1021A formed at the bottomside of the base 10A. Since either the first surface 204A or the secondsurface 205A of the elastic member 20A is disposed inside the thrustgroove 102A, either the first end surface 202A or the second end surface204A couples with the stopping surface 1021A. Therefore, the elasticmember 20A will not be rotated with respect to the base 10A after acertain amount of torsional forces is applied on the elastic member 20A.In general, the thrust groove 102A is adapted to support the elasticmember 20A being securely arranged inside the mounting cavity 101A andperpendicularly arranged on the bottom surface of the base 10A. And, thestopping surface 1021A is adapted to prevent the elastic member 20Ainstalled inside the mounting cavity 101A being rotated by the torsionalforces, in such manner that the torsional force applied on the elasticmember 20A is converted into the deformation of the elastic member 20A,so as to storage these torsional forces into the elastic element 20A.

As shown in FIG. 14, the base 10A further comprises a fastening hole103A formed on the bottom surface of an interior of the base 10A,wherein the retention arrangement 50A is passed through the fasteninghole 103A to rotatably mount the tension arrangement 40A on the base10A. The base 10A further comprises a thrust member 11A formed at anouter edge of the mounting cavity 101A of the base 10A, wherein thethrust member 11A defines a first sliding groove 111A, wherein two endsof first sliding groove 111A are integrally extended from an thrust endof the thrust member 11A, such that the retention arrangement 40Adisposed within the base 10A can be rotated along the first slidinggroove 111A. In other words, the angular displacement of the retentionarrangement 40A with respect to the base 10A (the rotational movement ofthe retention arrangement 40A with respect to the base 10A) isconfigured by the size of the first sliding groove 111A. And, the base10A further comprises at least one affixing member 12A outwardly andintegrally extended from the mounting cavity 10A, wherein the affixingmember 12A is adapted to install the tensioner on an external device.

The damping member 30A is able to rotate towards an unloading directionand a loading direction, as shown in FIGS. 10 and 11. As shown in FIG.13, the damping member 30A comprises a damping body 31A and a dampingcover 32A, wherein the damping cover 32A wraps on an outer circumferenceof the damping body 31A, so while the damping member 30A is disposedinside the mounting cavity 101A of the base 10A, the damping cover 32Acontacts with an inner wall of the mounting cavity 101A of the base 10A,so as to provide certain amounts of frictional forces. In general, thedamping body 31A has a rigid structure. The damping body 31A can be madeof cast steels, powder metallurgy components, or other material having apredetermined amount of strength and an easily-molding structure. Thedamping cover 32A is made of elastic material, wherein the elasticmaterial can be wear-resistant materials. In order to improve thefrictional coefficient of the damping cover 31A, a plurality ofanti-slip strips is provided on the damping cover 31A. Accordingly, thedamping body 31A further comprises a main body 311A and a second slidinggroove 310A formed on an inner-bottom portion of the main body 311A. Inorder to ensure the damping member 30A smoothly sliding along the innerwall of the mounting cavity 101A of the base 10A, the damping member 30Ais designed to have an arc-shape, so the second sliding groove 310A ofthe main body 311A is also formed in an arc-shaped structure, whereinthe arc-shaped second sliding groove 31 OA is adapted to match with theshape of the first surface 204A of the elastic member 20A, so the firstsurface 204A of the elastic member 20A is wrapped within the secondsliding groove 310A.

The main body 311A of the damping body 31A comprises a first forcingsurface 3111A (i.e. the fourth end surface), a second forcing surface3112A (i.e. the third end surface), a upper forcing surface 3113A, abottom forcing surface 3114A, and an outer forcing surface 3115A,wherein the second sliding groove 310A is formed between the bottomforcing surface 3114A and the outer forcing surface 3115A, and apredetermined distance (thickness) is formed between the upper forcingsurface 3113A and the bottom forcing surface 3114A. The first forcingsurface 3111A is located on a first sidewall (at the right side) of themain body 31A, and the second forcing surface 3112A is located on anopposed second sidewall (at the left side) of the main body 31A, and thedamping cover 32A is coupled on the outer side of the outer forcingsurface 3115A. The second sliding groove 31 OA is arranged on the firstsurface 204A of the elastic member 20A, and the upper forcing surface3113A must be maintained in a horizontal state while the damping member30A is placed on the elastic member 20A. However, the first surface 204Aof the elastic member 20A is a helical shape, so the height of the firstsurface 204A of the elastic member 20A is gradually increased, and insuch manner that a thickness from the upper forcing surface 3113A andthe bottom forcing surface 3114A is not constant. The thickness betweenthe upper forcing surface 3113A and the bottom forcing surface 3114A atthe first forcing surface 3111A (the thicker portion) is larger than thethickness between the upper forcing surface 3113A and the bottom forcingsurface 3114A at the second forcing surface 3112A (the thinner portion).The thicker portion of the damping member 30A is to contact the lowerpoint of the first surface 204A of the elastic member 20A and thethinner portion of the damping member 30A is to contact the higher pointof the first surface 204A of the elastic member 20A. Therefore, whilethe damping member 30A is placed on the elastic member 20A, the uppersurface 3113A of the damping member 30A is parallel to the bottomsurface of the base 10A. It is worth mentioning that while the elasticmember 20A is rotated downwardly as well as that the damping member 30Ais coupled with the elastic member 20A, the first forcing surface 3111Acontacts with the first surface 204A of the elastic element 20A, so asto stop the damping member 30A being downwardly rotate by the firstsurface 204A of the elastic member 20A. While the elastic member 20A isinstalled into the base 10A as well as that the damping member 30A isinstalled on the elastic member 20A, the damping cover 32A coupled onthe damping member 30A contacts with the inner wall of the mountingcavity 101A, so the first surface 204A defined on the first end face101A of the elastic member 20A is sliding along the inner wall of themounting cavity 101A. Therefore, the elastic member 20 can prevent therelative sliding movement between the damping member 30A and the innerwall of the mounting cavity 101A.

Referring to FIG. 12 to FIG. 13 of the drawings, the tension arrangement40A comprises a tension body 41A, a pushing member 42A disposed insidethe tension body 41A, and a tension wheel member 43A integrally extendedfrom the tension body 41A, wherein the tension body 41A has a tensionhole 401A to communicate with the fastening hole 103A of the base 10A,and in such manner that the retention arrangement 50A is able to passthrough the tension hole 401A of the tension body 41A and the fasteninghole 103A of the base 10A respectively, so as to couple the tensionarrangement 40A and the base 10A together. The tension body 41A has aninner chamber 410A, and comprises a projected member 411A provided on anouter edge of the tension body 41A, wherein the pushing member 42Adisposed inside the inner chamber 410A. While the retention arrangement40A is installed on the base 10A, the projected member 411A is disposedinside the first sliding groove 111A of the thrust member 11A of thebase 10A. That is to say, the projected member 411A is sliding along thefirst sliding groove 111A of the base 10A. Therefore, the rotationaldisplacement between the tension arrangement 40A and the base 10A isdetermined by the projected member 411A and the first sliding groove111A. In other words, the rotational displacement between the tensionarrangement 40A and the base 10A is limited within one end of the firstsliding groove 111A of the thrust member 11A to the other end thereof.

In particular, the pushing member 42A comprises a pushing main body 421Aformed at an inner surface of the pushing member 42A and one or morereinforcing members 422A, wherein the pushing main body 421A isdownwardly extended from the inner surface of the pushing member 42A,and the reinforcing members 422A are formed between the pushing mainbody 421A and the inner surface of the pushing member 42A to securelyattach the pushing main body 421A and the pushing member 42A together,so as to reinforce the structure of the pushing main body 421A.Specifically, the structure of the pushing main body 421A is a circulararc-shaped structure, and the total arc length of the pushing main body421A and the damping member 30A is smaller than the entirecircumferential length of the elastic element 20A. The size of thepushing main body 421A matches with the elastic member 20A. Inparticular, when the tension arrangement 40A is mounted on the base 10A,the pushing main body 421A is adapted to wrap around at least a portionof an outer circumference of the elastic member 20A, so as to wrap thefirst surface 204A of the elastic member 20A. Accordingly, since thefirst surface 204A of the elastic member 20A is helical shape, the innersurface of the tension body 41A which contacts with the first surface204A of the elastic member 20A has a height difference structure.Therefore, the pushing main body 421A also has the height differencestructure. It is worth mentioning that the pushing main body 421Acomprises a forcing surface 4211A. The forcing surface 4211A contactswith the second forcing surface 3112A of the damping member 30A whilethe tension arrangement 40A is rotated with respect to the base 10A, soas to transfer the torsional force applied on the tension arrangement40A to the damping member 30A.

As shown in FIG. 12, the tension wheel member 43A comprises a tensionwheel 431A, wherein the tension wheel 431A is rotatably connected to thetension body 41A, and the torsional forces from the external device istransmitted to the tension body 41A by the tension wheel 431A.

Accordingly, the second surface 205A of the elastic member 20A islocated at the thrust groove 102A formed on a bottom portion of the base1 OA, wherein the second end surface 203A defined at a second surface205A of the elastic member 20A contacts with the stopping surface 1021Aof the thrust groove 102A, and the stopping surface 1021A is able tostop the rotation of the elastic member 20A so as to store the torsionalforces applied on the elastic member 20A into the elastic member 20A.The damping member 30A is located on the first surface 204A of theelastic element 20A, such that the first forcing surface 3111A of thedamping member 30A couples with the first end surface 202A of theelastic member 20A while the first surface 204A thereof contacts withthe bottom forcing surface 3114A of the damping member 30A. The forcingsurface 4211A of the pushing member 42A contacts with the second forcingsurface 3112A of the damping member 30A, so the damping cover 32Acontacts with the inner wall of the mounting cavity 101A of the base10A. The first surface 204A of the elastic member 20A is arranged withinthe second sliding groove 31 OA. Therefore, the torsional forces appliedon the tension arrangement 40A is able to transfer to the damping member30A by the pushing member 42A, and then the damping member 30A is ableto transmit the torsional forces to the elastic member 20A and thetorsional forces is stored into the elastic member 20A.

In particular, while the damping member 30A is rotated in the loadingdirection, the damping member 30A will receive two different directionsof forces to generate a huge amount of damping, which is a huge amountof frictional force. At the same time, the abrasion loss of the dampingcover 32A has slightly small effect to the angle of the torque for theelastic member 20A, so the change of the torque of the elastic member20A is relative small.

In particular, when the tensioner is operated towards the loadingdirection, a pushing force is applied on the second forcing surface3112A of the damping member 30A by the forcing surface 4211A of thepushing main body 421A of the pushing member 42A, and then the pushingforce is transmitted to the elastic member 20A by the first forcingsurface 3111A of the damping member 30A, so as to cause the deformationof the elastic member 20A, i.e. the radial expansion thereof. Therefore,the first end surface 202A and the second end surface 203A of theelastic member 20A are radially expanded to enlarge the diameter of theelastic member 20A.

As shown in FIG. 16, a second positive tension P3 is applied on theinner wall of the mounting cavity 101A (i.e. the inner cylindricalsurface) by the first surface 204A of the elastic member 20A. Inparticular, the pushing forces applied on the elastic member 20A by thefirst forcing surface 3111A of the damping member 30A will generate areaction force P1 towards the inner wall of the mounting cavity 101A. Inaddition, an action force P towards the inner wall of the mountingcavity 101A is applied to the second forcing surface 3112A of thedamping member 30A by the pushing member 42A, and then the action forceP and the reaction force P1 are combined together to form a firstpositive tension P2. The directions of the first positive tension P2 andthe second positive tension P3 are the same, so the directions thereofare both towards the inner wall of the mounting cavity 101A. Therefore,the damping member 30A receives two positive tensions at the same timeas well as that the damping member 30A is rotated towards the loadingdirection, so as to improve the frictional force provided by thetensioner of the present invention.

One skilled in the art will understand that the embodiment of thepresent invention as shown in the drawings and described above isexemplary only and not intended to be limiting.

It will thus be seen that the objects of the present invention have beenfully and effectively accomplished. The embodiments have been shown anddescribed for the purposes of illustrating the functional and structuralprinciples of the present invention and is subject to change withoutdeparture from such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

What is claimed is:
 1. A tensioner, comprising: a base having an innercylindrical surface; a shaft rotatably extended into said base; atension arrangement which comprises a projected member rotatably coupledat said base; a damping member disposed in said base and being driven torotate by said projected member, wherein said damping member has africtional surface frictionally engaged with said inner cylindricalsurface of said base; and an elastic member, which is disposed in saidbase, having a first end surface biasing against to bias against aninner surface of said damping member and an opposed second end surfacebiasing against a bottom side of said base, wherein when said shaft isrotated with respect to said base, said projected member not only pushessaid damping member to rotate within said base for frictionally slidesaid frictional surface of said damping member on said inner cylindricalsurface of said base so as to generate a first positive tension, butalso expands said elastic member radially to generate a second positivetension, such that said first positive tension and said second positivetension are generated at the same time to enhance a damping force ofsaid tensioner.
 2. The tensioner, as recited in claim 1, wherein saidbase further has a mounting cavity and a stopping surface formed at saidbottom side of said base, wherein said elastic member is disposed atsaid mounting cavity for biasing against said stopping surface of saidbase.
 3. The tensioner, as recited in claim 2, wherein said base furtherhas a thrust groove formed at said bottom side of said base to form saidstopping surface thereof.
 4. The tensioner, as recited in claim 3,wherein a depth of said thrust groove is gradually decreased to matchwith a gradient of said second end surface of said elastic member. 5.The tensioner, as recited in claim 1, wherein said damping member has anarc-shaped defining two ends and forming a third end surface and afourth end surface at said two ends of said damping member respectively,wherein said third end surface of said damping member couples with saidfirst end surface of said elastic member, and said fourth end surface ofsaid damping member couples with said projected member of said tensionarrangement.
 6. The tensioner, as recited in claim 2, wherein saiddamping member has an arc-shaped defining two ends and forming a thirdend surface and a fourth end surface at said two ends of said dampingmember respectively, wherein said third end surface of said dampingmember couples with said first end surface of said elastic member, andsaid fourth end surface of said damping member couples with saidprojected member of said tension arrangement.
 7. The tensioner, asrecited in claim 4, wherein said damping member has an arc-shapeddefining two ends and forming a third end surface and a fourth endsurface at said two ends of said damping member respectively, whereinsaid third end surface of said damping member couples with said firstend surface of said elastic member, and said fourth end surface of saiddamping member couples with said projected member of said tensionarrangement.
 8. The tensioner, as recited in claim 5, wherein athickness of said damping member is gradually reduced from said fourthend surface of said damping member to said third end surface thereof tomatch with a gradient of a first surface of said elastic member wheresaid first end surface is formed thereat.
 9. The tensioner, as recitedin claim 6, wherein a thickness of said damping member is graduallyreduced from said fourth end surface of said damping member to saidthird end surface thereof to match with a gradient of a first surface ofsaid elastic member where said first end surface is formed thereat. 10.The tensioner, as recited in claim 7, wherein a thickness of saiddamping member is gradually reduced from said fourth end surface of saiddamping member to said third end surface thereof to match with agradient of a first surface of said elastic member where said first endsurface is formed thereat.
 11. The tensioner, as recited in claim 2,wherein said base further comprises a thrust member formed at an outeredge of said mounting cavity to define a first sliding groove at twoends of said thrust member, where said projected member is slid alongsaid first sliding groove of said base.
 12. The tensioner, as recited inclaim 4, wherein said base further comprises a thrust member formed atan outer edge of said mounting cavity to define a first sliding grooveat two ends of said thrust member, wherein said projected member is slidalong said first sliding groove of said base.
 13. The tensioner, asrecited in claim 10, wherein said base further comprises a thrust memberformed at an outer edge of said mounting cavity to define a firstsliding groove at two ends of said thrust member, wherein said projectedmember is slid along said first sliding groove of said base.
 14. Thetensioner, as recited in claim 11, further comprising a retentionarrangement serving as said shaft to couple with said base and saidtension arrangement to ensure said elastic element and said dampingmember to be retained between said base and said tension arrangement,wherein said tension arrangement further comprises a tension body havinga tension hole for said shaft passing therethrough to couple with saidbase, wherein said projected member is provided at an outer edge of saidtension body to slide along said first sliding groove of said base. 15.The tensioner, as recited in claim 12, further comprising a retentionarrangement serving as said shaft to couple with said base and saidtension arrangement to ensure said elastic element and said dampingmember to be retained between said base and said tension arrangement,wherein said tension arrangement further comprises a tension body havinga tension hole for said shaft passing therethrough to couple with saidbase, wherein said projected member is provided at an outer edge of saidtension body to slide along said first sliding groove of said base. 16.The tensioner, as recited in claim 13, further comprising a retentionarrangement serving as said shaft to couple with said base and saidtension arrangement to ensure said elastic element and said dampingmember to be retained between said base and said tension arrangement,wherein said tension arrangement further comprises a tension body havinga tension hole for said shaft passing therethrough to couple with saidbase, wherein said projected member is provided at an outer edge of saidtension body to slide along said first sliding groove of said base. 17.A method for enhancing a damping force of a tensioner, comprising thesteps of: (a) rotating a shaft within a base to drive a projected memberof a tension arrangement to rotate; (b) driving a damping member torotate within said base by said projected member to frictionally slide africtional surface of said damping member on an inner cylindricalsurface of said base so as to generate a first positive tension; and (c)radially expanding an elastic member within said base to generate asecond positive tension, wherein said first positive tension and saidsecond positive tension are generated at the same time to enhance adamping force of said tensioner.
 18. The method, as recited in claim 17,wherein the step (c) further comprises a step of disposing said elasticmember in said base at a position that a first end surface of saidelastic member is biased against to bias against an inner surface ofsaid damping member and an opposed second end surface of said elasticmember is biased against a bottom side of said base.
 19. The method, asrecited in claim 17, wherein the step (b) further comprises the stepsof: (b.1) configuring said damping member to have an arc-shape anddefining two ends and forming a third end surface and a fourth endsurface at said two ends of said damping member respectively; (b.2)coupling said third end surface of said damping member with said firstend surface of said elastic member; and (b.3) coupling said fourth endsurface of said damping member with said projected member of saidtension arrangement.
 20. The method, as recited in claim 17, wherein thestep (a) further comprises the steps of: (a.1) providing a tension bodywhich has a tension hole for said shaft passing therethrough to couplewith said base; and (a.2) locating said projected member at an outeredge of said tension body.